/* Copyright (C) 2004 Manuel Novoa III <mjn3@codepoet.org> * * GNU Library General Public License (LGPL) version 2 or later. * * Dedicated to Toni. See uClibc/DEDICATION.mjn3 for details. */ #include "_stdio.h" /* Both ftell() and fseek() (for SEEK_CUR) need to correct the stream's * position to take into account buffered data and ungotten chars. * * If successful, store corrected position in *pos and return >= 0. * Otherwise return < 0. * * If position is unrepresentable, set errno to EOVERFLOW. */ int attribute_hidden __stdio_adjust_position(register FILE * __restrict stream, register __offmax_t *pos) { __offmax_t oldpos; int corr; if ((corr = stream->__modeflags & __MASK_READING) != 0) { --corr; /* Correct for ungots. Assume narrow, and fix below. */ } #ifdef __UCLIBC_HAS_WCHAR__ if (corr && __STDIO_STREAM_IS_WIDE(stream)) { /* A wide stream and we have at least one ungotten wchar. * If it is a user ungot, we need to fail since position * is unspecified as per C99. */ if ((corr > 1) || stream->__ungot[1]) { /* User ungetwc, */ return -1; /* so position is undefined. */ } corr -= (1 + stream->__ungot_width[1]); if (stream->__state.__mask > 0) { /* Incomplete (bad?) mb char. */ corr -= stream->__ungot_width[0]; } } #endif #ifdef __STDIO_BUFFERS corr += (((__STDIO_STREAM_IS_WRITING(stream)) ? stream->__bufstart : stream->__bufread) - stream->__bufpos); #endif oldpos = *pos; /* Range checking cases: * (pos - corr > pos) && (corr > 0) : underflow? return -corr < 0 * (pos - corr > pos) && (corr < 0) : ok .. return -corr > 0 * (pos - corr <= pos) && (corr >= 0) : ok .. return corr > 0 * (pos - corr <= pos) && (corr < 0) : overflow .. return corr < 0 */ if ((*pos -= corr) > oldpos) { corr = -corr; } if (corr < 0) { __set_errno(EOVERFLOW); } return corr; }